1. Field of the Invention
The present invention relates to a spraying apparatus for spraying a liquid such as water or paint and, more specifically, to improvements in an adjusting mechanism for adjusting the spraying condition of a spraying apparatus.
2. Description of the Prior Art
Simple spraying apparatus are disclosed, for example, in U.S. Pat. Nos. 2,494,837 and 3,445,068. Such a well-known spraying apparatus is shown in FIG. 10. Referring to FIG. 10, indicated at 1 is a main housing fixedly holding a solenoid 2 incorporating an armature 3. A grip 4 provided with a switch unit 5 is extended downward from the main housing 1. An AC voltage is applied to the solenoid 2 by operating the switch unit 5 to vibrate the armature 3 laterally. A pump housing 1A is fixed to the front side of the main housing 1 with a fixing screw 6. A cylinder 7 is disposed within the pump housing 1A so as to extend laterally. A piston 8 is fitted into the cylinder 7 and a compression spring 9 is interposed between the piston 8 and the cylinder 7. The piston 8 is reciprocated within the cylinder 7 by the positive action of the armature 3 caused by energizing the solenoid 2 and resilient action of the compression spring 9. A cap 10 is formed integrally with the pump housing 1A at the lower side of the same. A vessel 11 for containing a liquid such as water or paint is screwed on the threaded portion 12 of the cap 10. Suction holes 13 and discharge holes 14 are formed in the pump housing 1A and the cap 10. The upper end of a suction pipe 15 is fitted into the suction hole 13 of the cap 10. A strainer 16 is attached to the lower end of the suction pipe 15 so as to enclose the inlet of the suction pipe 15. A nozzle holder 17 is screwed on the front end of the pump housing 1A so as to hold a valve 18, a compression spring 19 and a nozzle 20 in place within the front end of the pump housing 1A. A housing cover 1B is fixed to the main housing 1 with screws 21 to cover the solenoid 2 and the armature 3. An adjusting member 22 is screwed through a compression spring 23 on the main housing 1. The amplitude of vibration of the armature 3 is adjustable by means of the adjusting member 22.
The amplitude of vibration of the armature is decided by adjusting the distance between the front end face 22A of the adjusting member 22 and the rear end face of a stopper 24 provided on the main housing 1 to stop the armature 3 when the same is attracted by the magnetic action of the solenoid 2. The stroke of the piston 8 is adjusted by varying the distance to regulate the condition of the mist of the liquid sprayed through the nozzle 20. Accordingly, when the solenoid 2 is energized, the armature 3 vibrates between the adjusting member 22 and the stopper 24, and thereby the piston 8 is reciprocated within the cylinder 7 by the positive action of the armature 3 and the resilient action of the compression spring 9. The liquid, such as water or paint, contained in the vessel 11 is sucked through the suction pipe 15 into the cylinder 7 by the suction stroke of the piston 8, and then the liquid is compressed within the cylinder 7, the valve 18 provided at the opening of the cylinder 7 is opened against the resilient force of the compression spring 19 so that the liquid is allowed to flow into the front end of the cylinder 7 through the gap between the opening of the cylinder 7 and the valve 18 and the liquid is sprayed through the nozzle hole of the nozzle 20 by the compression stroke of the piston 8.
Thus in the conventional spraying apparatus, the condition of the mist to be sprayed through the nozzle 20 is regulated by adjusting the amplitude of vibration of the armature 3 by turning the adjusting member 22, however, this spraying apparatus does not have any standard for adjusting the spraying condition, and hence the adjusting member 22 is apt to be turned excessively, and thereby the amplitude of vibration of the armature is enhanced excessively and the solenoid 2 is often overloaded.